The study consists of a double-blind, randomized, placebo controlled trial with imipramine in 80 agoraphobic patients without significant depression-dysphoria and in the absence of concurrent encouragement and/or instructions to enter phobic situations in order to assess the extent of specific antipanic and antiphobic effects of the drug with as little contamination as possible. Treatment groups each consisting of 20 subjects include placebo and three different weight-adjusted imipramine dosages e.g., 0.5 mg/kg per day, 1.5 mg/kg per day or 3 mg/kg per day over an eight week period preceded by a single-blind two-week placebo phase to eliminate placebo responders. The specific aim of the study is to delineate and stratify dose response relationships for the central agoraphobic symptoms i.e., panic, phobia, avoidance behavior to first determine the optimum dose/plasma concentration response relationships which would indicate specific and possibly differential mechanisms of drug action on these various symptom dimensions.